Fluid injection device, and mechanical system equipped with such a device

ABSTRACT

A device for injecting a fluid into a mechanical system that may undergo heating, comprising at least one body containing a thermally triggered charge generating combustion gas, ignition of the charge being able to be triggered under the action of an ignition command and/or under the effect of a heat contribution, from a heating area of the body toward the charge, a reservoir containing the fluid, means for fastening the device to the mechanical system, the fastening means adapted to put the reservoir in fluid communication with the mechanical system, and means for delivering pressurized fluid outside the reservoir through the action, directly or through intermediate means, of the combustion gases. Within the device, the fastening means comprise at least one injection sleeve provided with an outer thread coated with an anti-loosening adhesive film. The invention also relates to a mechanical system equipped with at least one such device.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of the U.S. patentapplication Ser. No. 13/705,485 filed on Dec. 5, 2012, which claimspriority to French Patent Application No. 11 61230 filed on Dec. 6,2011. The contents of each of which are incorporated herein by referencein their entirety.

BACKGROUND

The present invention relates to a device for injecting a fluid into amechanical system, for example an anti-friction bearing, main bearing orball joint. The invention also relates to a mechanical system equippedwith such a device. The invention relates to the field of securitydevices, in particular in the aeronautics field. Mechanical systems ofthe rolling bearing, main bearing or ball joint type are commonlyincorporated into all types of automobile, railroad, aeronautic orindustrial machine equipment. For example, the mechanical system can bea ball bearing incorporated into an aeronautical device, such as ahelicopter rotor.

In a known manner, such a mechanical system can undergo heating duringoperation. Beyond a critical temperature, certain component elements ofthe system can be irreparably damaged. The operation of the equipmentinto which the system is incorporated is then hindered, or even abruptlystopped. In certain cases, such a malfunction can therefore cause aserious accident.

In order to prevent or slow the heating of mechanical systems, a numberof lubrication devices are known. Furthermore, the mechanical system canbe provided with signaling devices, such as temperature sensors, makingit possible to anticipate critical heating.

International Publication WO/2008/107579 (“PCT '579”) describes amechanical system equipped with an autonomous device for injecting afluid, in particular a lubrication or cooling fluid, into the system incase of heating. The device comprises a thermally triggered pyrotechniccharge generating combustion gas arranged in a housing. The fluid iscontained in a reservoir separated from the charge by a moving piston onthe one hand, and from the system by a membrane on the other hand. Byreaching a predetermined ignition temperature, the charge undergoescombustion and the generated gases pressurize the fluid in thereservoir. The membrane breaks under the pressure from the fluid, whichis then injected into the mechanical system. The structure and operationof the device, as well as its thermal connection with the system, areoutlined by PCT '579. However, the conditions for integration of thedevice into the system are not fully satisfactory.

The aim of the present invention is to propose an improved device forinjecting a lubrication or cooling fluid. In particular, the inventiontargets a device that performs well and is reliable under demandingoperating conditions, while being inexpensive and easy to implement.

SUMMARY

To that end, the invention relates to a device for injecting a fluidinto a mechanical system that may undergo heating, the device having atleast:

-   -   a body containing a thermally triggered charge generating        combustion gas, ignition of the charge being able to be        triggered under the action of an ignition command and/or under        the effect of a heat contribution, from a heating area of the        body toward the charge,    -   a reservoir containing the fluid,    -   means for fastening the device to the mechanical system, the        fastening means being adapted to put the reservoir in fluid        communication with the mechanical system, and    -   means for delivering pressurized fluid outside the reservoir        through the action, directly or through intermediate means, of        the combustion gases.

According to the invention, the fastening means comprise at least oneinjection sleeve provided with an outer thread coated with an adhesiveanti-loosening coating. The injection sleeve is formed from a materialhaving a 0.2% deformation yield strength Re_(0.2) comprised between 500and 700 MPa on the one hand, and a tensile strength Rmax comprisedbetween 700 and 900 MPa on the other hand. The means for delivering thepressurized fluid outside the reservoir comprise a non-fragmentablemembrane, which initially covers the reservoir and breaks when thepressure of the fluid in the reservoir exceeds a predetermined pressurethreshold. The membrane is located in a volume delimited by the outerthread of the injection sleeve. The flow rate of the pressurized fluidoutside the reservoir is regulated, either with a periodic delivery offluid over a reduced time interval, shorter than five seconds, or aregular and continuous delivery of fluid over a period of severalminutes, or an intermittent delivery of fluid, through successiveinjections, over several minutes.

The invention thus makes it possible to improve the device's resistanceto vibrational stresses, the sealing between the device and themechanical system, and the precision of the delivery of the fluid in thesystem. The device is configured to operate under at least one mode offluid delivery, advantageously predetermined according to the intendedapplication. The device ensures a quick intervention in the event ofheating of the system, in particular when the system is susceptible toundergo contact heating between its component elements during operation.Thus, the damage that may be suffered by the component elements of thesystem under the effect of critical heating is limited.

According to other advantageous features of the device according to theinvention, considered alone or in combination:

-   -   The reservoir is housed in the body containing the charge, a        moving piston is inserted between the fluid and the charge, and        the injection sleeve protrudes from the body at the heating area        of the body.    -   The reservoir is distinct from the body or bodies containing the        charge(s), the intermediate compression means for compressing        the fluid in the reservoir comprise at least one guide duct for        guiding the combustion gases to a moving piston in contact with        the fluid, and the injection sleeve protrudes from the        reservoir.    -   The device comprises means for signaling the combustion of the        charge.    -   The device comprises a miniaturized electronic unit for        transferring information to a remote central unit.    -   The device is autonomous, the ignition of the charge being able        to be triggered only under the effect of a heat contribution,        from a heating area of the body, toward the charge.

The invention also relates to a mechanical system, for example ananti-friction bearing, a main bearing, or a ball joint, equipped with atleast one device as described above.

According to other advantageous features of the system according to theinvention, considered alone or in combination:

-   -   The injection sleeve of the device is screwed into a tapped hole        formed in the mechanical system.    -   The tapped hole is formed in a part of the system made from a        steel having a tensile strength comprised between 2400 and 2600        MPa, still more preferably approximately 2500 MPa.    -   The mechanical system is equipped with several devices each        provided with at least one charge having a different triggering        temperature from the other charges.    -   At least one positive braking element cooperating with a device        is integrated into the mechanical system.    -   The positive braking element is of the sheet metal brake type.    -   The positive braking element is of the locking type.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood upon reading the followingdescription, provided solely as a non-limiting example and done inreference to the appended drawings, in which:

FIG. 1 is a perspective view of an autonomous device for injectingfluid, said device being according to the invention;

FIG. 2 is an axial cross-sectional view of the device in plane II ofFIG. 1, equipping a mechanical system, partially shown, also accordingto the invention;

FIG. 3 is a smaller scale cross-sectional view of the device and thesystem of FIG. 1, integrated into a test bench implemented during apreparatory phase for the manufacture of the device;

FIG. 4 is a graph illustrating the operation of the device of FIGS. 1and 3;

FIG. 5 is another graph illustrating the operation of the device ofFIGS. 1 and 3, with a different parameterization;

FIG. 6 is a cross-sectional view of another mechanical system, equippedwith three devices of FIGS. 1 to 3;

FIG. 7 is a graph illustrating the operation of the devices and thesystem of FIG. 6;

FIG. 8 is a cross-sectional view similar to FIG. 5 of another mechanicalsystem, equipped with four devices according to an example of theinvention;

FIG. 9 is a cross-sectional view similar to FIG. 2 of a device accordingto a further example of the invention;

FIG. 10 is a cross-sectional view similar to FIG. 2 of a deviceaccording to another example of the invention;

FIG. 11 is a cross-sectional view similar to FIG. 2 of a deviceaccording to yet another example of the invention, equipping anothermechanical system also according to the invention; and

FIG. 12 is a cross-sectional view similar to FIG. 11 of a deviceaccording to a an example of the invention, equipping another mechanicalsystem also according to the invention.

DETAILED DESCRIPTION

FIGS. 1 to 3 show an autonomous device 10 according to the invention forinjecting a fluid F.

More specifically, the device 10 is a miniaturized cartridge designed toequip a mechanical system 1, also according to the invention, that mayundergo heating. The system 1 is partially shown in FIG. 2 forsimplification purposes on the one hand, and is fully shown in FIG. 3,integrated into a test bench B1, on the other hand.

In the example of FIGS. 2 and 3, the system 1 is of the ball bearingtype, with an outer ring 2 and an inner ring 6, stationary and rotatingrespectively during operation of the bench B1. An at least partiallytapped orifice 3 passes through the ring 2, connecting an outer surface4 and an inner space 5 to said ring 2. Ball bearings 7 are housed inside5 the system 1, along a raceway formed between the rings 2 and 6.Preferably, the rings 2 and 6 are made from a steel with a very highhardness, having a tensile strength comprised between 2400 and 2600megapascal (MPa), still more preferably approximately 2500 MPa. Thebench B1 comprises a stationary portion B11 secured to the ring 2 and amoving portion B12 secured to the ring 6. In this way, the portion B12and the ring 6 can be rotated around an axis X1, the system 1 thenperforming its anti-friction function.

During operation of the system 1, the cartridge 10 aims to protect theinside 5 and the moving parts 6 and 7 from heating. To that end, thefluid F is on the one hand initially contained in the cartridge 10 atrest, and on the other hand injected from the cartridge 10 toward thesystem 1, under certain operating conditions, during operation of thesystem 1 and the cartridge 10.

In one alternative not shown, the system 1 may be another mechanicalsystem that may undergo heating, for example a ball joint or a mainbearing.

According to another alternative not shown, the cartridge 10 may bepositioned at another location of the system 1, for example on a frontsurface.

The cartridge 10 includes a body 20, a sleeve 30 for fastening thecartridge 10 to the mechanical system 1, a thermally triggered charge 40that may generate combustion gas, a reservoir 60 adapted to contain thefluid F, means 68 for delivering the fluid F outside the reservoir 60,as well as intermediate means 70 for compressing the fluid F in thereservoir 60. The cartridge 10 is generally axially symmetrical around acentral axis X10.

The body 20 is centered on the axis X10 and comprises a base 22, a cover26, and the sleeve 30 secured to the base 22. The base 22 comprises acylindrical wall 23 centered on the axis X10 and a radial wall 24perpendicular to the axis X10. Optionally, the wall 23 has an outersurface provided with ribs 25 facilitating handling of the body 20. Aheating area Z24 is delimited on the outer side of the wall 24, aroundthe sleeve 30. Said area Z24 is provided to be positioned in contactwith the outer surface 4 of the system 1, so that a heat transfer canoccur through the wall 24 from the system 1 toward the charge 40. Thebase 22 is preferably made from a metal material with a high thermalconductivity, such as a copper, zinc and/or aluminum alloy, for examplebrass.

The cover 26 forms a basin, whereof the section in a plane containingthe axis X10 generally forms an inverted U. The base 22 and the cover 26together delimit a housing 29 formed inside the body 20. Arranged in thehousing 29 are the charge 40, the means 70, and the reservoir 60containing the fluid F, the rest initially being filled withnon-pressurized air. The base 22 and the cover 26 are assembled to oneanother and secured at a junction area 28, for example by welding orgluing. In the example of FIG. 2, the wall of the cover 26 partiallycovers the wall 23 of the base 22. As a non-limiting example, themaximum diameter of the body 20 at the junction area 28 is approximately20 mm. The cover 26 can be made from a less expensive material than thebase 22.

Preferably, the cover 26 has, at its apex, i.e. at the hollow portion ofthe U, a portion 27 that can be deformed under the effect of a pressureinside the body 20, when the combustion gas of the charge 40 is diffusedin the housing 29. The strength of the portion 27 may be reduced underthe effect of a heat treatment prior to assembling the cover 26 on thebase 22, or by decreasing the thickness of the portion 27 relative tothe rest of the cover 26, or using any other means suited to thisapplication. Alternatively, the portion 27 may be an element fastened onthe cover 26, for example made from a plastic that is plasticallydeformable without breaking under the pressure and temperature of thecombustion gases of the charge 40. Thus, the combustion of the charge 40can be detected visually from outside the cartridge 10, for exampleduring a maintenance operation, the portion 27 then being deformedtoward the outside of the body 20.

The sleeve 30 is secured to the base 22 and protrudes from the wall 24,on the side opposite the cover 26. More specifically, the sleeve 30forms a cylindrical wall centered on the axis X10 and having an outerthread 32 on the one hand, and an inner bore on the other handdelimiting a duct 36 for delivering the fluid F outside the cartridge10. As one non-limiting example, the outer diameter of the sleeve 30 isapproximately 6 mm. In order to ensure optimal fastening of thecartridge 10 to the system 1, the outer thread 32 is coated with ananti-loosening adhesive film 34, then screwed into the correspondingorifice 3 of the system 1, with a controlled torque. The orifice 3,specifically provided to receive the sleeve 30, is at least partiallytapped. As one non-limiting example, the film 34 applied on the thread32 may be a glue or an adhesive paste with a strong adhesive power, inparticular a cyanoacrylate glue.

The body 20, and in particular the sleeve 30, are configured to ensureoptimal operating efficiency of the cartridge 10 and the mechanicalsystem 1. In particular, the material and expense of the area Z24, thematerial and the dimensions of the sleeve 30, the dimensional precisionand the strength of the thread 32, the nature and quantity of film 34applied on the thread 32, and the tightening torque of the threadedsleeve 30 in the orifice 3 of the system 1 are particularly importantfor the implementation of the cartridge 10. The sleeve 30 makes itpossible to integrate the cartridge 10 into the system 1 while ensuringsatisfactory strength of the cartridge 10 with respect to thevibrational stresses transmitted to it by the system 1, satisfactorysealing of the system 1 at the orifice 3, and delivery of the fluid Finto a specific area of the inside 5 of the system 1. The area Z 24allows rapid and precise ignition of the charge 40 in response tocritical heating of the system 1. In this way, the cartridge 10 has areduced response time, ensures rapid intervention in the event ofheating of the system 1, and limits the damage potentially suffered bythe component elements of the system 1 under the effect of criticalheating.

Advantageously, the sleeve 30 is made from a material having a 0.2%deformation yield strength Re_(0.2) comprised between 500 and 700 MPa,preferably between 550 and 650 MPa, still more preferably approximately600 MPa. Furthermore, the material of the sleeve has a tensile strengthRmax comprised between 700 and 900 MPa, preferably between 750 and 850MPa, still more preferably approximately 800 MPa. Such mechanicalcharacteristics can for example be obtained with a steel alloy, with orwithout thermal treatment. Thus, the sleeve 30 and its thread 32 have asatisfactory strength with respect to the mechanical, vibrational andthermal stresses undergone in contact with the system 1.

Complementarily, a positive braking element, not shown, may beintegrated into the system 1. This element is for example of the sheetmetal brake or lockwire type and cooperates with the cartridge 10, so asto avoid unscrewing of said cartridge 10 under the action of thevibrations of the system 1 during operation.

The reservoir 60 comprises a cylindrical wall 62 that is centered on theaxis X10 and extends between an open end provided with a circularopening 64 and a closed end formed by a radial wall 66. Preferably, thereservoir 60 suitable for storing the fluid

F is made from a material with a lower thermal conductivity than thematerial of the body 20 receiving the charge 40. In this way, the fluidF to be injected can be preserved from any heating that may come fromheating of the system 1 to be protected, at the heating area Z24. Forexample, the reservoir 60 may be made from a light material, such as aplastic.

A membrane 68, for example made up of a frangible plastic or metal film,is formed on the wall 66 of the reservoir 60. When the reservoir 60 ispositioned on the base 22, the wall 66 presses on the inner surface ofthe wall 24, while the membrane 68 protrudes inside the duct 36,perpendicular to the axis X10. The membrane 68 is then located in thevolume delimited by the contours of the thread 32, advantageously beingbrought closer to the outlet end of the duct 36 and the inside 5 of thesystem 1. Alternatively, the membrane 68 may be formed in the same planeas the wall 66, or may completely replace the wall 66. The membrane 68performs a first function of sealing the reservoir 60 and a secondfunction of delivering, after rupture, fluid F outside the reservoir 60.The membrane 68 and the duct 36 constitute the means for delivering thefluid F outside the reservoir. The sleeve 30 may be described as aninjection sleeve, inasmuch as it is passed through by the fluid F whenthe latter is delivered.

Preferably, the membrane 68 is non-fragmentable in case of rapture, inother words configured to tear without fragments under thepressurization force of the fluid F in the reservoir 60. In fact, themigration of membrane fragments 68 toward the inside 5 of the system 1via the duct 36 would risk damaging the system 1.

In the example of FIG. 2, the compression means 70 are inserted betweenthe fluid F and the housing 29 containing the charge 40. These means 70are necessary when the mixture of the combustion gases with the fluid Fto be injected is troublesome and/or when the injection of the mixtureof combustion gas and fluid F can be problematic. More specifically, themeans 70 comprise a piston 72 initially positioned in the reservoir 60at the opening 64. The piston 72 is provided with a lateral cylindricalwall 73 bearing against the wall 62, on a first side 74 oriented towardthe housing 29 and with a second side 75 oriented toward the inside ofthe reservoir 60 and the fluid F. The second side 75 is initiallypositioned in contact with the fluid F, which is then subjected to azero or low pressure. When combustion gases are released from the charge40, the pressure increases in the housing 29, destroying the equilibriumbetween the pressure exerted by the fluid F on the side 75 and thepressure exerted by the gases on the side 74. The piston 72 moves in thereservoir 60 with the wall 73, which slides against the wall 62,compressing the fluid F until the membrane 68 breaks. Then, the piston72 continues to push into the reservoir 60, with a flow F80 of the fluidF that escapes the reservoir 60 through the pierced membrane 68, towardthe duct 34 and the mechanical system 1.

In an alternative not shown in FIGS. 1 and 2, the means 70 may comprisea deformable membrane, or any other element suited for this application.

The fluid F may be a lubrication, protection, or cooling agent for thecomponent elements of the mechanical system 1. The fluid F may consistof a liquid, emulsion, gel, oil, or paste, potentially charged withsolid elements such as powders. The fluid F may also consist of amixture of several fluids of different natures, in particular a mixtureof at least two fluids chosen from among those listed above. As anexample, the fluid F is an oil suited for emergency oiling of amechanical bearing. In other words, the fluid F may be any type ofactive agent or mixture of agents suitable for the applications coveredby the invention. The characteristics of the fluid F, in particular itsviscosity, lubricating potential and/or cooling potential, arepreferably chosen specifically for the targeted application.

The charge 40 is positioned in the housing 29 of the body 20, betweenthe wall 23 of the base 22 and the wall 66 of the reservoir 60. Theexact volume of the housing 29 occupied by the charge 40 depends on itscomposition, and therefore the targeted application. The rest of thehousing 29 is occupied by air when the cover 26 covers the base 22.Alternatively, the charge 40 may occupy a more or less significantportion of the housing 29.

The charge 40 generates combustion gas when it burns above apredetermined temperature. Known from PCT '579 are thermally triggeredcharges, the ignition of which may result from an outside heatcontribution or may be triggered by a remotely controlled ignition.Parameters such as the quantity and composition of the charge 40influence the injection kinematics of the fluid F. The choice of thematerial for the base 22, in particular at the area Z24, alsoparticipates in controlling the response time the lapsing between themoment when abnormal heating of the system 1 takes place, the moment ofdetection of that abnormal heating corresponding to ignition of thecharge 40, and the injection moment of the fluid F into the system 1.Once the ignition is done, the charge 40 burns quickly, between severalmilliseconds and several seconds.

The management of the different aforementioned parameters makes itpossible to set the formal triggering temperature, control the quantityof gas generated and the pressure of the gases before injection of thefluid, from several bars to several hundreds of bars, control thecombustion time of the charge 40, and control the length and flow rateof delivery of the fluid F. The parameterization of the cartridge 10 mayin particular be optimized to avoid premature injection of the fluid Fdue to untimely temperature spikes. In other words, an adjustableignition delay of the charge 40 makes it possible not to triggerauto-triggering of the composition during periodic overheating of thesystem 1 not characteristic of a malfunction.

The generation of combustion gases of the charge 40 may correspond totwo primary embodiments. According to a first embodiment, the gas comesonly from the combustion of a thermally triggered charge 40 generatinggas, for example mixing thermite and gas-generating compounds. Accordingto a second embodiment, the gas comes from the serial combustion ofsuperimposed charges, which comprise variable portions of thermallytriggered compounds under the effect of the heat contribution of thesystem 1, gas-generating compounds, and compounds acting as ignitionrelays. For example, in this second embodiment, the charge 40 maycomprise a first thermally triggered combustion stage, a second ignitionrelay stage, and a third combustion gas generating stage.

Preferably, the device 10 is autonomous, i.e. provided with no ignitioncontroller. In that case, the ignition of the charge 40 is triggeredonly under the effect of the heat contribution, from the heating areaZ24 of the body 20 toward the charge 40.

Alternatively, the device 10 may be equipped with a remote ignitioncontrol.

In practice, the pressure increase of the fluid F in the reservoir 60 isensured by the membrane 68, the piston 72, and the combustion gases. Thefluid F is released from the reservoir 60 when the membrane 68 is torn,when the pressure of the fluid F in the reservoir 60 increases above apredetermined pressure.

Furthermore, the test bench B1 may be used to test differentparameterizations of the cartridge 10, during a preparatory phase formanufacture of the cartridge 10 that will ultimately be integrated intothe system 1, as explained hereafter relative to FIGS. 4, 5 and 7.

FIG. 4 shows a graph illustrating the operation of the cartridge 10 witha given parameterization.

To that end, the cartridge 10 is fastened on the anti-friction bearing1, which in turn is mounted on the test bench B1, as shown in FIG. 3.The graph of FIG. 4 shows a temperature T° in degrees Celsius (° C.) ofthe anti-friction bearing 1 as a function of the time t in minutes(min). More specifically, the evolution of the temperature T1 ismeasured at the outer surface 4 by a measuring probe connected to acomputer, not shown for simplification reasons.

In order to reproduce the targeted aeronautic applications, the test isconducted with a strong charge exerted on the anti-friction bearing 1,i.e. a contact pressure between the rings 2, 6 and the balls 7 comprisedbetween 2.5 and 2.8 MPa, as well as a high speed of rotation around theaxis X1, in the vicinity of 10,000 revolutions/minute. The anti-frictionbearing 1 is an anti-friction bearing manufactured from material 10006,with a bore of 30 mm and balls with diameters of 7.144 mm.

The rotation of the inner ring 6 starts at initial moment t0, where thesurface 4 has a temperature T0 corresponding to the ambient temperatureand pressure conditions. The temperature T° increases rapidly in theanti-friction bearing 1 during operation, then more gradually, until, ata moment tm, first bonds appear inside the anti-friction bearing 1. Thetemperature T° continues to increase up to a moment t1 corresponding toa temperature T1 for triggering the cartridge 10. As an example, themoment t1 occurs after approximately 30 minutes, while the temperatureT1 is approximately 135° C. Between ignition of the charge 40 andinjection of the fluid F into the anti-friction bearing 1, a duration inthe vicinity of several seconds elapses, negligible on the scale of thegraph. The heat divergence, reflecting the imminent seizing of theanti-friction bearing 1 by bonds, is stopped. The temperature T° dropsagain immediately and for several minutes, under the effect of the fluidF delivered to the inside 5 of the anti-friction bearing 1. Lastly, thetemperature T° begins to increase again at a moment t2, where the fluidF is dissipated and/or its effects are no longer sufficient to preventheating of the anti-friction bearing 1. At a moment t3, the temperatureT° again reaches the temperature T1, but without a new injection offluid F being possible.

At that stage, the readings indicate that the use of the cartridge 10gave the anti-friction bearing 1 an operating suspension during aninterval At of approximately 30 minutes, between the moments t1 and t2.In other words, the operating time of the anti-friction bearing 1 isdoubled owing to the cartridge 10.

FIG. 5 shows a graph illustrating the operation of the cartridge 10,with a different parameterization from that of FIG. 4.

The cartridge 10 is triggered at a moment t11 and a temperature T10 andceases producing effects at a moment t12. As an example, the moment t11occurs after approximately 30 minutes, while the temperature T10 isapproximately 135° C. Between t11 and t12, during an interval Δt10, thetemperature T° substantially maintains a plateau slightly lower thanT10. The parameterization of the cartridge 10 allows distribution of thefluid F in the anti-friction bearing 1 throughout the entire intervalΔt10. For example, the nature of the fluid F is such that itsredistribution in the anti-friction bearing 1 is slow and gradual, andits effects are extended over the entire interval Δt10. According toanother example, the configuration of the cartridge 10 is such that theinjection of the fluid F into the anti-friction bearing is slow andgradual throughout the entire interval Δt10. As an example, the intervalΔt10 is approximately 30 minutes.

FIG. 6 shows an anti-friction bearing 101 according to the invention,equipped with three cartridges 10 of FIGS. 1 to 3.

Certain component elements of the anti-friction bearing 101 arecomparable to the component elements of the anti-friction bearing 1 ofthe first embodiment, described above, and bear the same referencesincreased by 100. These are the outer ring 102, the tapped orifices 103,the surface 104, the inner space 105, the inner ring 106, the balls 107,and the axis of rotation X101. The differences with respect to the firstembodiment are primarily found in the assembly of the anti-frictionbearing 101 and the number of cartridges 10.

A shaft 120 is secured to the ring 106, such that the ring 102 ismounted between two portions 130 and 140 of a piece of equipmentpartially shown. The portion 140 includes a housing 141 in which thecartridges 10 are mounted. Optionally, the housing 141 also includes aminiaturized electronic unit 150, diagrammatically shown by a block indotted lines, suitable for communicating with the outside of theequipment. This unit 150 is for example a temperature sensor at a givenpoint of the system 1, or a command to ignite charges contained in thecartridges 10. This assembly is shown as a non-limiting example, withthe understanding that the anti-friction bearing 101 may be suited toany type of assembly and application.

The three cartridges 10 are fastened to respective orifices 103 formedthrough the ring 102, near one another. More specifically, the sleeves30 are screwed into the orifices 103, with the areas Z24 in contact withthe surface 104. The proximity between cartridges 10 in particularresults from a compromise between their bulk and the productionconstraints of the tapped orifices 103. Preferably, each of thecartridges 10 is configured to release its fluid after a giventemperature or after a certain exposure time to a given temperature.More specifically, the set of cartridges 10 comprises a cartridge 11configured to trigger first, a cartridge 12 configured to triggersecond, and a cartridge 13 configured to trigger third. To that end, thecharges of the various cartridges 10 are preferably made up differentlyfrom one another, so as to trigger with a time offset. The materialthickness of the bodies of various cartridges may also have differences.

FIG. 7 shows a graph illustrating the operation of the system 101equipped with the cartridges 11, 12, and 13.

The cartridge 11 is triggered at a temperature T21 and a moment t21.After an interval Δt21, the cartridge 12 is triggered at a temperatureT22 and a moment t22. After an interval Δt22, the cartridge 13 istriggered at a temperature T23 and a moment t23. After the moment t21,the operating state of the system 101 extends for an interval Δt23. Thetemperature T21 is below the temperature T22, which is below thetemperature T23. The temperatures T21, T22 and in particular thetemperature T23 are chosen so that the cartridges 11, 12, 13 triggerbefore critical heating of the system 101. As an example, thetemperatures T21, T22 and T23 are respectively approximately 150° C.,155° C. and 160° C. Thus, the overall state of the system 101corresponds to the sum of the intervals Δt21, Δt22 and Δt23 and isimproved relative to a system equipped with a single cartridge 10.

FIG. 7 intentionally illustrates a non-optimal parameterization of thecartridges 10. In fact, the interval Δt21 is relatively reduced withrespect to the intervals Δt22 and Δt23. In other words, the cartridge 12triggers while the effects of the fluid F delivered by the cartridge 11may not have dissipated. Preferably, the parameterization of thecartridges 11 to 13 is such that each of the intervals Δt21, Δt22 andΔt23 is maximized, without a cartridge being triggered while the effectsof the fluid F delivered by the previous cartridge have not yetdissipated.

FIG. 8 shows an anti-friction bearing 201 according to the inventionequipped with four cartridges 10′ according to a second embodiment ofthe invention.

Certain component elements of the anti-friction bearing 201 arecomparable to the component elements of the anti-friction bearing 101,described above, and bear the same references increased by 100. Theseare the inner ring 202, the tapped orifices 203 in the ring 202, theinner surface 204, the inner space 205 of the anti-friction bearing 201,the outer ring 206, the balls 207, and the axis of rotation X201. Thedifferences with respect to the previous embodiment are primarily foundin the assembly of the anti-friction bearing 201, as well as the numberand configuration of the cartridges 10′.

A stationary hollow shaft 220 is secured to the ring 202, while the ring206 is secured to a rotating hollow shaft 230. The cartridges 10′ aremounted in a bore 221 of the shaft 220, as well as an optional unit 250comparable to the unit 150 previously described. More specifically, thecartridges 10 are fastened in respective orifices 203 formed through theshaft 220 and the ring 202, while being radially distributed at 90°around the axis X201 of the anti-friction bearing 201 and the shaft 220.

The only difference in the cartridges 10′ and the cartridges 10 is thatthe cartridges 10′ are provided with a different sleeve 30′ from thesleeve 30. More specifically, the sleeve 30′ is more elongated so as topass through the shaft 220, such that its thread can be screwed into thecorresponding orifice 203. The reactivity of the cartridges 10′ isslightly reduced due to their distance from the inside 205 and themoving elements 206, 207 of the anti-friction bearing 201, withoutdetriment to the protection of the anti-friction bearing 201. Theelongation of the sleeves 30′ is required here by the particularassembly of the anti-friction bearing 201.

Other assemblies of mechanical systems equipped with cartridges similarto the cartridges 10 and 10′ can be considered without going beyond thescope of the invention. The systems may be associated with one or morecartridges. In particular, several independent cartridges allow aplurality of injections by thermal triggering at least at two differentheating temperatures, and at least one location of the system likely toundergo heating.

FIG. 9 shows a third embodiment of a device 310 according to theinvention. Certain component elements of the cartridge 310 arecomparable to the component elements of the cartridge 10 of the firstembodiment, described above, and bear the same references increased by300. These are the body 320 centered on an axis X310, the walls 323 and324, the housing 329, the threaded sleeve 330, the thread 332, the film334, the duct 336, the charge 340, the reservoir 360, the membrane 368,and the piston 372 for compressing the fluid F in the reservoir 360. Thedifferences relative to the first embodiment are primarily in thestructure of the body 320.

The wall 324 of the body 320 forms an outer protruding shoulder relativeto the wall 323, such that the heating area Z324 is more expansive thanthe areas Z24. Alternatively, the wall 324 may be more or less radiallyextended as a function in particular of the assembly constraints of thecartridge 310. At the membrane 368, the reservoir 360 bears against aninner shoulder 337 of the sleeve 330. The sleeve 330 is more elongatedthan the sleeve 30, without, however, distancing the membrane 368 fromthe outlet of the duct 336. When the sleeve 330 is elongated along theaxis X310, the reservoir 360 can be elongated accordingly. The cartridge310 is thus well suited, for example, to the assembly constraints of thesystem 201 of FIG. 8.

The body 320 does not include a cover 26 and deformable portion 27. Thebody 320 includes an end 326 opposite the sleeve 30, which is providedwith means 350 for signaling the triggering of the charge 340. On theside of the end 326, the housing 328 comprises a bore 327 having alarger diameter than the diameter of the rest of the housing 329. Anannular groove 328 is formed in said bore 327. An annular seal 357 ispositioned in the bore 327, then a substantially annular glazed element352 is positioned against the seal 357. Another annular seal 358 is thenpositioned in the annular groove 328, such that the glazed element ishoused between the seals 357 and 358. The state of the charge 340 and/orthe combustion gases is thus transparently visible through the glazedelement 352. In other words, the combustion of the charge 340 may bedetected visually from outside the cartridge 310, for example during amaintenance operation.

In an alternative not shown, the signaling means 350 may be configureddifferently without going beyond the scope of the invention. Forexample, the element 352 is not transparent, but made from aheat-sensitive material changing color in contact with the combustiongases.

FIG. 10 shows a fourth embodiment of a cartridge 410 according to theinvention.

Certain component elements of the cartridge 410 are comparable to thecomponent elements of the cartridge 10 of the first embodiment,described above, and bear the same references increased by 400. Theseare the body 420 centered on an axis X410, the base 422, the cover 426,the deformable portion 427, the housing 429, the threaded sleeve 430,the thread 432, the film 434, the duct 436, the shoulder 437, the charge440, the reservoir 460, the membrane 468, and the piston 472 forcompressing the fluid F in the reservoir 460.

The cartridge 410 combines certain elements of the cartridges 10 and310. In particular, the means for signaling triggering of the charge 440are made up of the deformable portion 427 integrated into the cover 426,while the sleeve 430 and the reservoir 460 may be more or less elongatedalong the axis X410.

The cartridge 10 is nevertheless more compact than the cartridges 310and 410, in the longitudinal direction defined by its central axis X10.

FIG. 11 shows a fifth embodiment of a device 510 equipping a mechanicalsystem 501 according to the invention.

In particular, the device 510 is configured like a syringe, providedwith a charge 540 and a reservoir 560 for fluid F that are distant fromeach other.

Certain component elements of the system 501 and the device 510 arecomparable to the component elements of the system 1 and the device 10of the first embodiment, described above, and bear the same referencesincreased by 500. These are the outer ring 502, the orifice 503, theinside 505 of the system 501, the body 520 delimiting a housing 529 forreceiving a charge 540, the base 522, the cover 526, the threaded sleeve530 secured to the base 522, the reservoir 560, the membrane 568, andthe means 570 for compressing the fluid F in the reservoir 560, thesemeans 570 comprising a piston 572.

The reservoir 560 is not positioned in the body 520. Only the charge 540is arranged in the housing 529 of the body 520, which is fastened in theorifice 503 of the system 501 by the sleeve 530. The reservoir 560 isprovided with its own body. More specifically, the reservoir 560 isarranged between a support assembly 582 situated at its downstream endand a support assembly 584 situated at its upstream end, the upstreamand downstream directions being defined by the direction of delivery ofthe fluid F into the system 501.

The assembly 582 comprises the membrane 568 and a threaded sleeve 590suitable for being fastened in a tapped orifice 509 of the system 501.The sleeve 590 is an injection sleeve for the fluid F, while the sleeve530 is an exposure sleeve for the charge 540. The sleeve 590 iscomparable to the sleeve 530, both comprising an outer thread and ananti-loosening adhesive film. The diameter of the sleeve 590 is smallerthan the diameter of the sleeve 530, and likewise, the diameter of theorifice 509 is smaller than the diameter of the orifice 503. The heatingarea of the body 520 includes the sleeve 530 and the portion of the baseclose to that sleeve 530. Thus, the charge 540 and the membrane 568 arepositioned near the inside 505 of the system 501, which allows bothrapid ignition of the thermally triggered charge 540 and rapid deliveryof the fluid F by the membrane 568, as in the preceding embodiments.

In an alternative not shown in FIG. 11, the membrane 568 is positionedin the sleeve 590, in a volume delimited by the contours of the threadof said sleeve 590.

The assembly 584 forms a cover covering the upstream end of thereservoir 560, which is provided with a piston 572. Since the housing529 is far away from the reservoir 560, a duct 576 connecting thehousing 529 and the assembly 584 is provided to guide the combustiongases. The duct 576 extends from the cover 526 configured as a pneumaticconnector toward the assembly 584, to which another pneumatic connector579 is integrated. In other words, the intermediate means 570 forcompressing the fluid F in the reservoir 560 comprise the piston 572,the guide duct 576, the connector 579, and the assembly 584.

Advantageously, the device 510 can comprise a significant quantity offluid F contained in the reservoir 560, so as to be able to protect thesystem 501 from critical heating over an extended period of time. Tothat end, the assembly 582, the membrane 568, and the sleeve 590 can beconfigured to control the flow rate of the fluid F outside the reservoir560. Thus, when the charge 540 is triggered and the combustion gasesbear on the piston 572 while passing through the duct 576, the injectionof fluid F into the system 501 can be regulated.

The device 510 is nevertheless more bulky than the miniaturizedcartridges 10, 10′, 310 and 410. In other words, the device 510 issuitable for particular applications where bulk is not a decisivefactor.

FIG. 12 shows a sixth embodiment of a device 610 equipping a mechanicalsystem 601 according to the invention.

In particular, the device 610 is configured like a syringe, providedwith several charges 640 distant from the fluid F reservoir 560.

Certain component elements of the system 601 and the device 610 arecomparable to the component elements of the system 501 and the device510 of the fifth embodiment, described above, and bear the samereferences increased by 100. These are the outer ring 602, the orifice603, the inside 605 of the system 601, the body 620 delimiting a housing629 for receiving a charge 640, the threaded sleeve 530 secured to thebody 620, the reservoir 660, the membrane 688, the means 670 forcompressing the fluid F in the reservoir 660, the piston 672, the duct676, the connector 679, the support assemblies 682 and 684, and thethreaded sleeve 690.

The device 610 comprises three bodies 620, each comprising a housing 629containing a charge 640. Preferably, the charges 640 are madedifferently from one another so as to have time-staggered triggering, asin the embodiment of FIGS. 6 and 8. Each body 620 is fastened by athreaded sleeve 630 and an orifice 603 formed in the ring 602 of thesystem 601. A duct 677 extends outside each housing 629 up to the mainduct 676. In this way, each housing 629 is connected to the assembly 684supporting the reservoir 660 and the piston 672. Preferably, each duct677 is provided with a unidirectional valve, such that the combustiongases cannot flow back into the other ducts 677.

In particular, the charges 640, the fluid F, and the means fordelivering the fluid F can be configured to allow several successiveinjections of fluid F into the system 601. The volume of fluid F in thereservoir 660 may be divided into several equivalent or distinct volumesF1, F2 and F3. When the first charge is triggered, the volume F1 isinjected into the system 601, then the injection is slowed, or evenstopped, for example due to the resistance opposed by the piston 672 tothe combustion gases. When the second charge is triggered, the volume F2is injected into the system 601 in turn. When the third charge istriggered, the volume F3 is injected into the system 601 in turn.

Other staged devices may be made, with a different structure but anoperation comparable to the device 660, without going beyond the scopeof the invention.

In an alternative not shown, each device according to the invention maybe provided with a miniaturized electronic unit for transferringinformation to a remote central unit, by wireless or wiredcommunication. For example, the miniaturized unit may comprise atemperature sensor and/or a pressure sensor arranged in the housing ofthe charge. The miniaturized unit may also serve as means for signalingtriggering of the charge. The miniaturized unit may be supplied withenergy by internal means or, alternatively, by the thermal energy givenoff by the combustion from the charge.

According to another alternative not shown, the devices, and inparticular the cartridges, may be positioned on the front surfaces ofthe anti-friction bearings, or at any point of the mechanical systemsadapted to the present application. In the case where the mechanicalsystem is a ball joint, the device may for example be positioned on ahousing formed in a tip body.

According to one alternative not shown, at least one positive brakingelement, for example of the sheet metal brake or lockwire type, may beintegrated into the system 1. Each device may be equipped with such anelement, so as to prevent it from being unscrewed under the action ofthe vibrations during operation of the system 1. This element iscomplementary to the fastening means, i.e. the threaded sleeve and theanti-loosening adhesive film.

Furthermore, all or some of the technical features of the differentembodiments may be combined with each other. Thus, the injection deviceand the mechanical system may be adapted to a particular application, inparticular in terms of cost, bulk, and operational constraints.

Whatever the embodiment, the invention may advantageously be implementedin safety, protection, or preventive maintenance contexts for mechanicalsystems of a nature to undergo heating. In particular, the invention hasa reliability and effectiveness adapted to the safety requirements inforce in the aeronautic field.

The invention claimed is:
 1. A device for injecting a fluid into amechanical system that may undergo heating, the device comprising: abody containing a thermally triggered charge generating combustion gas,ignition of the charge being able to be triggered under the action of anignition command and/or under the effect of a heat contribution, from aheating area of the body toward the charge, a reservoir containing thefluid, a fastener fastening the device to the mechanical system, thefastener adapted to put the reservoir in fluid communication with themechanical system, and a delivery device delivering pressurized fluidoutside the reservoir using combustion gases, and an intermediate devicecompressing the fluid in the reservoir, said intermediate devicecomprising at least one guide duct guiding the combustion gases to amoving piston in contact with the fluid, wherein the fastener compriseat least one injection sleeve provided with an outer thread coated withan adhesive anti-loosening coating, wherein the injection sleeve isformed from a material having a 0.2% deformation yield strength Re_(0.2)comprised between 500 and 700 MPa, and a tensile strength Rmax comprisedbetween 700 and 900 MPa, wherein the delivery device delivering thepressurized fluid outside the reservoir comprises a non-fragmentablemembrane, which initially covers the reservoir and breaks when thepressure of the fluid in the reservoir exceeds a predetermined pressurethreshold, wherein the membrane is located in a volume delimited by theouter thread of the injection sleeve, wherein the reservoir is distinctfrom the body containing the charge, wherein the injection sleeveprotrudes from the reservoir, and wherein the flow rate of thepressurized fluid outside the reservoir is regulated, with at least oneof: a regular and continuous delivery of fluid over a period of severalminutes; or an intermittent delivery of fluid, through successiveinjections, over several minutes.
 2. The device according to claim 1,wherein the device comprises a miniaturized electronic unit transferringinformation to a remote central unit.
 3. The device according to claim1, wherein the device is autonomous, the ignition of the charge beingable to be triggered only under the effect of a heat contribution, froma heating area of the body, toward the charge.
 4. A mechanical system,comprising an anti-friction bearing, a main bearing, or a ball joint,wherein the system is equipped with at least one device according toclaim
 1. 5. The mechanical system according to claim 4, wherein theinjection sleeve of said at least one device is screwed into a tappedorifice formed in the mechanical system.
 6. The mechanical systemaccording to claim 5, wherein the tapped orifice is formed in a part ofthe system made from a steel having a tensile strength comprised between2400 and 2600 megapascal (MPa).
 7. The mechanical system according toclaim 4, further comprising several of said at least one device eachprovided with at least one charge having a different triggeringtemperature from the other charges.
 8. The mechanical system accordingto claim 4, wherein at least one positive braking element cooperatingwith said at least one device integrated into the mechanical system. 9.The mechanical system according to claim 8, wherein the positive brakingelement is of the sheet metal brake type.
 10. The mechanical systemaccording to claim 8, wherein the positive braking element is of thelockwire type.